Though not labeled specifically on the modules, the first thing we noticed when we popped it into an nForce mainboard is that is has enhanced performance profiles embedded (EPP).

First off, SLI memory and EPP is the same thing. But what is SLI EPP memory? DDR2 DIMM memory uses an SPD (Serial Presence Detect) chip to store its JEDEC certified timings and setup specifications on. At default your mainboard reads this data so it can setup the timings and voltages needed according to the memory specifications.

Memory is configured at JEDEC specifications, the standard timings are not exactly enthusiast presets. Most of us know, we can do a heck of a lot more with memory timings and frequencies than the rather safe JEDEC SPD settings your BIOS uses by default.

Here's the trick, the SPD chip can hold much more data than is actually used. All that unused data is being written as ZERO; meaning it's largely unused space. A couple of brainy guys figured... hmm, let's talk to some memory vendors and see if we can do something with that extra space and utilize it for our new products to offer our buyers more options.

Once you overclock the system bus, your memory clock will run faster in MHz also, or if the memory can be clocked independently from the FSB. A higher FSB usually means that we'll need slower timings and/or different voltages, that kind of information could be stored into the SPD in several profiles.

So basically, additional non-JEDEC specified timings related towards a certain clock frequency or related to multipliers/dividers/voltages/drive strengths will be stored on that unused SPD space. This way that memory can be setup in a different way with the click of a button, or even better: Detected by your nForce 680i mainboard and set automatically. Now this is why you see NVIDIA slapped all over the memory, SLI Ready is a feature that can be found on the more expensive Series 6 NFORCE products from NVIDIA.

So in short: you can tweak memory really easy, yet this is intended for the folks that have a hard time overclocking themselves. It's a reasonably fool proof method of getting the best out of your DDR2 memory with an NFORCE series 680/780 mainboard. Obviously you can manage memory timings and everything related to it manually as well.

This is just an extra feature, yet the 6400C4DHX  we tested today has it embedded. Once you enable is this memory will jump from the safe 5-5-5-18 800 MHz timings towards 4-4-4-12 @ 800 MHz.

Now if your mainboard is not EPP/SLI ready, don't worry. You can always set these timings manually in the BIOS as well (at least with a decent mainstream mainboard).

How does RAM actually work ?

Adding RAM (random access memory) will normally cause your computer to feel faster on certain types of operations. Some applications (think Photoshop or most movie editing and animation packages) need bags of RAM to do their job. If you run them on a PC with too little RAM, they swap [Ed - Harddisk swapping / activity] constantly and run very slowly. You can get a massive speed boost by adding enough RAM to eradicate the swapping. Programs like these can seriously run 10 to 50 times faster once they have enough RAM.

But how does RAM work ? Well, the essence is actually very simple, we live in a digital world with 0's and 1's. To store a 1 in the memory cell, a capacitor is filled with electrons. To store a 0, it is emptied... that's it... it's that simple.

The dilemma with the capacitor's container is that it has a leak. In a matter of a few milliseconds a full bucket becomes empty. Therefore, for memory to work, either the CPU or the memory controller has to come along and recharge all of the capacitors holding a 1 before they discharge. To do this, the memory controller will read the memory and then writes it right back. This refresh operation happens automatically thousands of times per second.